642 lines
13 KiB
C
642 lines
13 KiB
C
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/* Buffer object implementation */
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#include "Python.h"
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typedef struct {
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PyObject_HEAD
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PyObject *b_base;
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void *b_ptr;
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int b_size;
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int b_offset;
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int b_readonly;
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long b_hash;
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} PyBufferObject;
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static int
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get_buf(PyBufferObject *self, void **ptr, int *size)
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{
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if (self->b_base == NULL) {
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assert (ptr != NULL);
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*ptr = self->b_ptr;
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*size = self->b_size;
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}
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else {
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int count, offset;
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getreadbufferproc proc;
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PyBufferProcs *bp = self->b_base->ob_type->tp_as_buffer;
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if ((*bp->bf_getsegcount)(self->b_base, NULL) != 1) {
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PyErr_SetString(PyExc_TypeError,
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"single-segment buffer object expected");
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return 0;
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}
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if (self->b_readonly)
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proc = bp->bf_getreadbuffer;
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else
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proc = (getreadbufferproc)bp->bf_getwritebuffer;
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if ((count = (*proc)(self->b_base, 0, ptr)) < 0)
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return 0;
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/* apply constraints to the start/end */
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if (self->b_offset > count)
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offset = count;
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else
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offset = self->b_offset;
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(char *)*ptr = (char *)*ptr + offset;
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if (self->b_size == Py_END_OF_BUFFER)
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*size = count;
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else
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*size = self->b_size;
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if (offset + *size > count)
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*size = count - offset;
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}
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return 1;
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}
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static PyObject *
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buffer_from_memory(PyObject *base, int size, int offset, void *ptr,
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int readonly)
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{
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PyBufferObject * b;
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if (size < 0 && size != Py_END_OF_BUFFER) {
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PyErr_SetString(PyExc_ValueError,
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"size must be zero or positive");
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return NULL;
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}
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b = PyObject_NEW(PyBufferObject, &PyBuffer_Type);
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if ( b == NULL )
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return NULL;
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Py_XINCREF(base);
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b->b_base = base;
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b->b_ptr = ptr;
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b->b_size = size;
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b->b_offset = offset;
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b->b_readonly = readonly;
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b->b_hash = -1;
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return (PyObject *) b;
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}
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static PyObject *
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buffer_from_object(PyObject *base, int size, int offset, int readonly)
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{
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if ( offset < 0 ) {
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PyErr_SetString(PyExc_ValueError,
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"offset must be zero or positive");
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return NULL;
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}
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/* if the base object is another buffer, then try to refer to the
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* base object.
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*/
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if ( PyBuffer_Check(base) && (((PyBufferObject *)base)->b_base) ) {
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base = ((PyBufferObject *)base)->b_base;
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offset = ((PyBufferObject *)base)->b_offset + offset;
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}
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return buffer_from_memory(base, size, offset, NULL, readonly);
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}
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PyObject *
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PyBuffer_FromObject(PyObject *base, int offset, int size)
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{
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PyBufferProcs *pb = base->ob_type->tp_as_buffer;
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if ( pb == NULL ||
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pb->bf_getreadbuffer == NULL ||
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pb->bf_getsegcount == NULL )
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{
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PyErr_SetString(PyExc_TypeError, "buffer object expected");
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return NULL;
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}
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return buffer_from_object(base, size, offset, 1);
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}
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PyObject *
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PyBuffer_FromReadWriteObject(PyObject *base, int offset, int size)
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{
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PyBufferProcs *pb = base->ob_type->tp_as_buffer;
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if ( pb == NULL ||
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pb->bf_getwritebuffer == NULL ||
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pb->bf_getsegcount == NULL )
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{
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PyErr_SetString(PyExc_TypeError, "buffer object expected");
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return NULL;
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}
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return buffer_from_object(base, size, offset, 0);
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}
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PyObject *
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PyBuffer_FromMemory(void *ptr, int size)
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{
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return buffer_from_memory(NULL, size, 0, ptr, 1);
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}
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PyObject *
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PyBuffer_FromReadWriteMemory(void *ptr, int size)
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{
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return buffer_from_memory(NULL, size, 0, ptr, 0);
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}
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PyObject *
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PyBuffer_New(int size)
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{
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PyObject *o;
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PyBufferObject * b;
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if (size < 0) {
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PyErr_SetString(PyExc_ValueError,
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"size must be zero or positive");
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return NULL;
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}
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/* Inline PyObject_New */
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o = PyObject_MALLOC(sizeof(*b) + size);
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if ( o == NULL )
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return PyErr_NoMemory();
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b = (PyBufferObject *) PyObject_INIT(o, &PyBuffer_Type);
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b->b_base = NULL;
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b->b_ptr = (void *)(b + 1);
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b->b_size = size;
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b->b_offset = 0;
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b->b_readonly = 0;
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b->b_hash = -1;
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return o;
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}
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/* Methods */
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static PyObject *
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buffer_new(PyTypeObject *type, PyObject *args, PyObject *kw)
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{
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PyObject *ob;
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int offset = 0;
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int size = Py_END_OF_BUFFER;
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if ( !PyArg_ParseTuple(args, "O|ii:buffer", &ob, &offset, &size) )
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return NULL;
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return PyBuffer_FromObject(ob, offset, size);
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}
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PyDoc_STRVAR(buffer_doc,
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"buffer(object [, offset[, size]])\n\
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\n\
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Create a new buffer object which references the given object.\n\
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The buffer will reference a slice of the target object from the\n\
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start of the object (or at the specified offset). The slice will\n\
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extend to the end of the target object (or with the specified size).");
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static void
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buffer_dealloc(PyBufferObject *self)
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{
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Py_XDECREF(self->b_base);
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PyObject_DEL(self);
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}
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static int
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buffer_compare(PyBufferObject *self, PyBufferObject *other)
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{
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void *p1, *p2;
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int len_self, len_other, min_len, cmp;
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if (!get_buf(self, &p1, &len_self))
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return -1;
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if (!get_buf(other, &p2, &len_other))
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return -1;
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min_len = (len_self < len_other) ? len_self : len_other;
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if (min_len > 0) {
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cmp = memcmp(p1, p2, min_len);
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if (cmp != 0)
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return cmp;
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}
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return (len_self < len_other) ? -1 : (len_self > len_other) ? 1 : 0;
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}
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static PyObject *
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buffer_repr(PyBufferObject *self)
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{
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char *status = self->b_readonly ? "read-only" : "read-write";
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if ( self->b_base == NULL )
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return PyString_FromFormat("<%s buffer ptr %p, size %d at %p>",
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status,
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self->b_ptr,
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self->b_size,
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self);
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else
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return PyString_FromFormat(
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"<%s buffer for %p, size %d, offset %d at %p>",
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status,
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self->b_base,
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self->b_size,
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self->b_offset,
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self);
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}
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static long
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buffer_hash(PyBufferObject *self)
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{
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void *ptr;
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int size;
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register int len;
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register unsigned char *p;
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register long x;
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if ( self->b_hash != -1 )
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return self->b_hash;
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/* XXX potential bugs here, a readonly buffer does not imply that the
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* underlying memory is immutable. b_readonly is a necessary but not
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* sufficient condition for a buffer to be hashable. Perhaps it would
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* be better to only allow hashing if the underlying object is known to
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* be immutable (e.g. PyString_Check() is true). Another idea would
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* be to call tp_hash on the underlying object and see if it raises
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* an error. */
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if ( !self->b_readonly )
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{
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PyErr_SetString(PyExc_TypeError,
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"writable buffers are not hashable");
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return -1;
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}
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if (!get_buf(self, &ptr, &size))
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return -1;
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p = (unsigned char *) ptr;
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len = size;
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x = *p << 7;
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while (--len >= 0)
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x = (1000003*x) ^ *p++;
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x ^= size;
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if (x == -1)
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x = -2;
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self->b_hash = x;
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return x;
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}
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static PyObject *
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buffer_str(PyBufferObject *self)
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{
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void *ptr;
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int size;
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if (!get_buf(self, &ptr, &size))
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return NULL;
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return PyString_FromStringAndSize(ptr, size);
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}
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/* Sequence methods */
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static int
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buffer_length(PyBufferObject *self)
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{
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void *ptr;
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int size;
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if (!get_buf(self, &ptr, &size))
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return -1;
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return size;
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}
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static PyObject *
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buffer_concat(PyBufferObject *self, PyObject *other)
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{
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PyBufferProcs *pb = other->ob_type->tp_as_buffer;
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void *ptr1, *ptr2;
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char *p;
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PyObject *ob;
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int size, count;
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if ( pb == NULL ||
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pb->bf_getreadbuffer == NULL ||
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pb->bf_getsegcount == NULL )
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{
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PyErr_BadArgument();
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return NULL;
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}
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if ( (*pb->bf_getsegcount)(other, NULL) != 1 )
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{
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/* ### use a different exception type/message? */
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PyErr_SetString(PyExc_TypeError,
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"single-segment buffer object expected");
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return NULL;
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}
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if (!get_buf(self, &ptr1, &size))
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return NULL;
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/* optimize special case */
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if ( size == 0 )
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{
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Py_INCREF(other);
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return other;
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}
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if ( (count = (*pb->bf_getreadbuffer)(other, 0, &ptr2)) < 0 )
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return NULL;
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ob = PyString_FromStringAndSize(NULL, size + count);
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p = PyString_AS_STRING(ob);
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memcpy(p, ptr1, size);
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memcpy(p + size, ptr2, count);
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/* there is an extra byte in the string object, so this is safe */
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p[size + count] = '\0';
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return ob;
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}
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static PyObject *
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buffer_repeat(PyBufferObject *self, int count)
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{
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PyObject *ob;
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register char *p;
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void *ptr;
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int size;
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if ( count < 0 )
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count = 0;
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if (!get_buf(self, &ptr, &size))
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return NULL;
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ob = PyString_FromStringAndSize(NULL, size * count);
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if ( ob == NULL )
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return NULL;
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p = PyString_AS_STRING(ob);
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while ( count-- )
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{
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memcpy(p, ptr, size);
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p += size;
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}
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/* there is an extra byte in the string object, so this is safe */
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*p = '\0';
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return ob;
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}
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static PyObject *
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buffer_item(PyBufferObject *self, int idx)
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{
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void *ptr;
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int size;
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if (!get_buf(self, &ptr, &size))
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return NULL;
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if ( idx < 0 || idx >= size ) {
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PyErr_SetString(PyExc_IndexError, "buffer index out of range");
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return NULL;
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}
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return PyString_FromStringAndSize((char *)ptr + idx, 1);
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}
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static PyObject *
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buffer_slice(PyBufferObject *self, int left, int right)
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{
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void *ptr;
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int size;
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if (!get_buf(self, &ptr, &size))
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return NULL;
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if ( left < 0 )
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left = 0;
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if ( right < 0 )
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right = 0;
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if ( right > size )
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right = size;
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if ( right < left )
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right = left;
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return PyString_FromStringAndSize((char *)ptr + left,
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right - left);
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}
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static int
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buffer_ass_item(PyBufferObject *self, int idx, PyObject *other)
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{
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PyBufferProcs *pb;
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void *ptr1, *ptr2;
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int size;
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int count;
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if ( self->b_readonly ) {
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PyErr_SetString(PyExc_TypeError,
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"buffer is read-only");
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return -1;
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}
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if (!get_buf(self, &ptr1, &size))
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return -1;
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if (idx < 0 || idx >= size) {
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PyErr_SetString(PyExc_IndexError,
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"buffer assignment index out of range");
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return -1;
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}
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pb = other ? other->ob_type->tp_as_buffer : NULL;
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if ( pb == NULL ||
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pb->bf_getreadbuffer == NULL ||
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pb->bf_getsegcount == NULL )
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{
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PyErr_BadArgument();
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return -1;
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}
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if ( (*pb->bf_getsegcount)(other, NULL) != 1 )
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{
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/* ### use a different exception type/message? */
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PyErr_SetString(PyExc_TypeError,
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"single-segment buffer object expected");
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return -1;
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}
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if ( (count = (*pb->bf_getreadbuffer)(other, 0, &ptr2)) < 0 )
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return -1;
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if ( count != 1 ) {
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PyErr_SetString(PyExc_TypeError,
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"right operand must be a single byte");
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return -1;
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}
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((char *)ptr1)[idx] = *(char *)ptr2;
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return 0;
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}
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static int
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buffer_ass_slice(PyBufferObject *self, int left, int right, PyObject *other)
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{
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PyBufferProcs *pb;
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void *ptr1, *ptr2;
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int size;
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int slice_len;
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int count;
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if ( self->b_readonly ) {
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PyErr_SetString(PyExc_TypeError,
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"buffer is read-only");
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return -1;
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}
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pb = other ? other->ob_type->tp_as_buffer : NULL;
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if ( pb == NULL ||
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pb->bf_getreadbuffer == NULL ||
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pb->bf_getsegcount == NULL )
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{
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PyErr_BadArgument();
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return -1;
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}
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if ( (*pb->bf_getsegcount)(other, NULL) != 1 )
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{
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/* ### use a different exception type/message? */
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PyErr_SetString(PyExc_TypeError,
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"single-segment buffer object expected");
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return -1;
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}
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if (!get_buf(self, &ptr1, &size))
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return -1;
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if ( (count = (*pb->bf_getreadbuffer)(other, 0, &ptr2)) < 0 )
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return -1;
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if ( left < 0 )
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left = 0;
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else if ( left > size )
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left = size;
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if ( right < left )
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right = left;
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else if ( right > size )
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right = size;
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slice_len = right - left;
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if ( count != slice_len ) {
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PyErr_SetString(
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PyExc_TypeError,
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"right operand length must match slice length");
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return -1;
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}
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if ( slice_len )
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memcpy((char *)ptr1 + left, ptr2, slice_len);
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return 0;
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}
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/* Buffer methods */
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static int
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buffer_getreadbuf(PyBufferObject *self, int idx, void **pp)
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{
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int size;
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if ( idx != 0 ) {
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PyErr_SetString(PyExc_SystemError,
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"accessing non-existent buffer segment");
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return -1;
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}
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if (!get_buf(self, pp, &size))
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return -1;
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return size;
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}
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static int
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buffer_getwritebuf(PyBufferObject *self, int idx, void **pp)
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{
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if ( self->b_readonly )
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{
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PyErr_SetString(PyExc_TypeError, "buffer is read-only");
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return -1;
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}
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return buffer_getreadbuf(self, idx, pp);
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}
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static int
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buffer_getsegcount(PyBufferObject *self, int *lenp)
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{
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void *ptr;
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int size;
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if (!get_buf(self, &ptr, &size))
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return -1;
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if (lenp)
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*lenp = size;
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return 1;
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}
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static int
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buffer_getcharbuf(PyBufferObject *self, int idx, const char **pp)
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{
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void *ptr;
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int size;
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if ( idx != 0 ) {
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PyErr_SetString(PyExc_SystemError,
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"accessing non-existent buffer segment");
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return -1;
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}
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if (!get_buf(self, &ptr, &size))
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return -1;
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*pp = (const char *)ptr;
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return size;
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}
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|
static PySequenceMethods buffer_as_sequence = {
|
|
(inquiry)buffer_length, /*sq_length*/
|
|
(binaryfunc)buffer_concat, /*sq_concat*/
|
|
(intargfunc)buffer_repeat, /*sq_repeat*/
|
|
(intargfunc)buffer_item, /*sq_item*/
|
|
(intintargfunc)buffer_slice, /*sq_slice*/
|
|
(intobjargproc)buffer_ass_item, /*sq_ass_item*/
|
|
(intintobjargproc)buffer_ass_slice, /*sq_ass_slice*/
|
|
};
|
|
|
|
static PyBufferProcs buffer_as_buffer = {
|
|
(getreadbufferproc)buffer_getreadbuf,
|
|
(getwritebufferproc)buffer_getwritebuf,
|
|
(getsegcountproc)buffer_getsegcount,
|
|
(getcharbufferproc)buffer_getcharbuf,
|
|
};
|
|
|
|
PyTypeObject PyBuffer_Type = {
|
|
PyObject_HEAD_INIT(&PyType_Type)
|
|
0,
|
|
"buffer",
|
|
sizeof(PyBufferObject),
|
|
0,
|
|
(destructor)buffer_dealloc, /* tp_dealloc */
|
|
0, /* tp_print */
|
|
0, /* tp_getattr */
|
|
0, /* tp_setattr */
|
|
(cmpfunc)buffer_compare, /* tp_compare */
|
|
(reprfunc)buffer_repr, /* tp_repr */
|
|
0, /* tp_as_number */
|
|
&buffer_as_sequence, /* tp_as_sequence */
|
|
0, /* tp_as_mapping */
|
|
(hashfunc)buffer_hash, /* tp_hash */
|
|
0, /* tp_call */
|
|
(reprfunc)buffer_str, /* tp_str */
|
|
PyObject_GenericGetAttr, /* tp_getattro */
|
|
0, /* tp_setattro */
|
|
&buffer_as_buffer, /* tp_as_buffer */
|
|
Py_TPFLAGS_DEFAULT, /* tp_flags */
|
|
buffer_doc, /* tp_doc */
|
|
0, /* tp_traverse */
|
|
0, /* tp_clear */
|
|
0, /* tp_richcompare */
|
|
0, /* tp_weaklistoffset */
|
|
0, /* tp_iter */
|
|
0, /* tp_iternext */
|
|
0, /* tp_methods */
|
|
0, /* tp_members */
|
|
0, /* tp_getset */
|
|
0, /* tp_base */
|
|
0, /* tp_dict */
|
|
0, /* tp_descr_get */
|
|
0, /* tp_descr_set */
|
|
0, /* tp_dictoffset */
|
|
0, /* tp_init */
|
|
0, /* tp_alloc */
|
|
buffer_new, /* tp_new */
|
|
};
|